Length compensating device



April 9, 1960 R. c. MQSER 2,933,074

LENGTH COMPENSATING DEVICE Filed Sept. 21, 1953 2 Shets-Sheet 1 if i V i.9 /76 L I; M 1?;

April 19, 1960 R. c. MOSER LENGTH COMPENSATING DEVICE.

2 Sheets-Sheet 2 Filed Sept. 21. 1953 LENGTH COMPENSATIN G DEVICE RobertC. Moser, Clearwater, Fla., assignor to B. C. Skinner, Jacques B.Skinner, B. L. Skinner, Bruce W. Skinner, and Vivien S. Miles,copartners, doing business as S-M Tappet Sales, Dunedin, Fla.

Appiication September 21, 1953, Serial No. 381,213

1t Claims. (Cl. 123-90) The present invention is directed to mechanicallength compensating means which are particularly useful as incorporatedin the operating linkages for valves of an internal combustion engine,and may be referred to as mechanical valve tappets but which may belocated at a point to contact directly the normal rotary cam or at someother point in the linkage of elements to the valve stem. The presentapplication is a continuation-in-part of my prior'application Serial No.189,695, filed October 12, 1950, now Patent No. 2,751,896, issued June26, 1956.

The invention comprises a length compensating device of. improved formadapted to maintain proper contact relation of the adjacent elements ofthe operating linkage and eliminate the need for clearance spacingtherein commonly known as lash and to reduce noises and maintain aproper timing of the engine valves and effect a proper seating thereof.

With my invention, a novel effective tappet structure is provided,automatically self-adjustable and which is usable both with. the cams ofcam shafts designed for the usual mechanical tappet operation, or forthe cams of cam shafts designed for hydraulic tappets which areautomatically adjustable, between which and valve stems or push rods noclearance or lash is present.

It is the primary object and purpose of my invention to provide a novel,exceptionally practical and eifective valve tappet, usable under allconditions of internal combustion engine design, either with enginesdesigned for mechanical tappets or hydraulic tappets, and which may beinstalled in new engines or used for replacement of tappets in enginesin service. An understanding of the invention may be had from thefollowing description, taken in connection with the accompanyingdrawings, in which:

Fig. l is a vertical section substantially on the plane of line Ii-1 ofFig. 3, through a tappet made in accordance with my invention, and shownin association with an operating cam therefor and an engine valve whichis opened or closed by the movements of the tappet, the parts of thetappet being shown in one position;

Fig. 2 is a fragmentary vertical section of the lower part of thetappet, with the parts thereof in another position which they takeduring engine operation;

Fig. 3 is a horizontal section and plan view, the section beingsubstantially on the plane of line 3-3 of Fig. 1;

Fig. 4 is a fragmentary section through the upper portion of the tappeton substantially the same plane as Fig. 1, the tappets in Figs. 1 and 4respectively slightly differing in structure for use, one in conjunctionwith intake valves of internal combustion engines, and the other withthe exhaust valves thereof;

Fig. is a vertical section of a portion of an engine a form 2,933,074Patented Apr. 19, 1960 ice showing the length compensating means in'adifferent a function similar to the spring washers of Figs. 1 and 4; and

Fig. 8 is a fragmentary horizontal section taken on line 8-8 of Fig. 2.

Like reference characters refer to like parts in thedifferent figures ofthe drawing.

The tappet includes in its structure a tappet body which has a closedhorizontal lower end 1 and cylindrical walls 2 integral therewith, thebody being open at its upper end, and having an oil drainage openingthrough the wall 2 near the lower end 1. With my invention the lowerside of the lower closed end 1 which bears against the actuating cam forthe tappet is in a plane inclined slightly to the horizontal or axis ofthe tappet. As indicated in Fig. 1 the lower face 1a is at a small angleto the plane 1b which is perpendicular to the tappet axis. The incline;tion may have different values dependent upon circumstances but willnormally lie within the range of .005 to .030 inch per lineal inch ofthe diameter of the tappet body. This is to prevent axial turning of thetappet body, and to give a positive uniform stress between the cam andsuch body. The function of thei'nclined bottomin combination with theinertia adjusting means will be described more fully hereinafter, butfor the present it is noted that for the proper operation of theadjusting means it is desirable to prevent rotation of the tappet incases where that can be reliably effected.

At the open upper end portion of the walls 2 of the body the interioropening is increased in diameter a small amount, providing an annularhorizontal shoulder below the upper end of the walls 2 against which aring 3 of metal is placed. An interiorly threaded sleeve 4 is formed atits upper end with an integral outwardly extending annular flange 5, theexterior diameter of which is slightly less than the interior diameterof the enlarged upper portion of the openings into the body. Flange 5 islocated over the ring 3 and the sleeve extends downwardly through thecentral opening of the ring.

"A specially constructed screw is threaded through the sleeve 4. Itincludes a head 6 at its upper end, from which-an exteriorly threadedsection 7 extends downwardly through the sleeve 4, and having itsuppermost threads below the uppermost threads of the sleeve to avoidvanish binding or wedging. Around the screw shank an annular groove 8 iscut at the lower end of the threaded section 7, below which is a shorterthreaded section 9, having a limited number of screw threads thereon.The shank of the screw is extended below the threaded section 9 in aplain cylindrical terminal section 10 from which a pin 11 extendsradially to one side. The threads are at a sufficiently fiat pitch thatthe screw will not turn in the sleeve from downward pressure on head 6.

A weight 12 is mounted on the section 10 for free turning thereabout.The pin 11 extends through a slot 13 provided in the weight 12 which isopen at its lower end at the lower end of the weight, and is of an arcspiralled upwardly and laterally as shown.

A nut 14 is screwed onto the lower short threaded section 9 of thescrew, having an annular recess at its upper end which receives a splitspring ring 15 in the 3 groove 8. Such ring serves as a stop againstwhich the nut comes when it is applied to the threaded section 9 andscrewed thereon. The distance between the upper side of the weight 12and the lower side of the nut 9 is such that when the weight .is in itsuppermost position (Fig. 2) the pin 11 is at the open lower end of theslot. The weight normally, by gravity, will drop to lower position as inFig. 1 with the pin at the upper closed end of the slot 13. V

The nut at opposite sides is recessed by recesses having sides at rightangles to each other, preferably, as shown at 16. Such nut around itsupper end portion is formedwith an integral outwardly extending flange17, beveled at its upper outer corners. The flange terminating atone ofthe recesses 16 which have been described, is cut away for a distanceback from each of the sides of the other recess 16, as shown at 18 inFig. 3.

A torsion spring 19 is located around the sleeve 4 which at its upperportion is of a greater diameter than at-its lower portion below aflange 20, similar to the flange 17, and having parts thereof removedsimilarly to the cut away portion 18 of flange 17. Flange Z is beveledat its lower outer corners. The diameter of the nut 14 between theflange 17 and a lower outwardly extending flange 14a thereon is likewisegreater than the lower portion of the sleeve 4. Therefore, theintermediate coils of the spring 19 between the nut 14 and the flange 20on the sleeve 4 is a short distance from the sleeve, while the lower endcoils of the spring 19 bind upon or are cinched against such nut 14 andthe upper coils cinched against the upper portion of sleeve 4. The endof the lower coil of the spring is bent inwardly in a hook 19a whichengages against the shoulder made at a recess 16, as shown in Fig. 3.The opposite end of the spring at its upper coil has a terminal portion1% extending through an opening in the flange of the interiorly threadedsleeve 4. A split spring ring retainer 21 of spring wire is received inan annular groove at the upper end portion of the walls 2 of the tappetbody and at the inner side thereof, against which the flange 5 of thesleeve 4, at its upper side, engages. Flanges 17 and20 prevent the lowerand upper end coils from movement in avertical direction.

By having the end coils of the spring 19 cinched upon the enlargedportion of sleeve 4 above the flange 20 and upon the nut 14respectively, the corresponding end hook portions 1% and 19a arerelieved of considerable stress as the spring is subjected to rapidlyrepeated variations in tensioning in the operation of the engine. Theinitial desired tensioning of spring 19 may be adjusted by progressivelyratcheting the hook portion 19a from one slot 16 to the .next in the nut14. It may be noted that the tension of spring 19 acts on nut 14 in adirection tending to screw it into engagement with stop ring 15. 'Whenthe tappets of the present invention are to be used in enginesoriginally equipped with the usual mechanical tappets and the linkagebetween the cam and engine valve has a certain amount of clearance orsocalled lash, then the tappets hereof are equipped with an auxiliaryspring means having a range of expansion and contraction correspondingto the amount of the original lash. In the form shown in Fig. 1 theauxiliary spring means comprises a dished washer 22 inserted between theflange 5 of the sleeve 4 and the supporting ring 3, and in Fig. 4 twosuch washers are employed in reversed relation to each other. Suchwasher or washers in strength are less than the valve spring with whichassociated, so that the dished washer or washers completely collapse ata load less than the pre-load of the valve spring. The washers in thetrade are commonly known as Bellville washers. The washers .are selectedto have a collapsible or contracting range in accordance with the camshape and clearance of the particular engine in which the present tappetis to be employed. Normally the exhaust valves have a greater clearancethan:

the inlet valves andconveniently the single washer of Fig. l may be usedfor the inlet valves and double washers as shown in Fig. 4 for theexhaust valves. As above" indicated, however, when the tappet of myinvention replaces tappets of either hydraulic or other forms in enginesin which no lash or clearance is originally pro-' vided and the cams areof appropriate design, the wasliers 22 are not needed.

In Fig. 6 another arrangement of spring washer means is shown. In thiscase the supporting ring 3 of Fig. 1 is omitted and the shell of thetappet 30 is provided with a thickened annular wall portion 31 providedwith an inclined shoulder 32. The bottom face of the flange portion 33of the nut 34 is similarly inclined and inserted between the opposedinclined faces is a. spr ng washer 35 which may be fiat. The amount ofspring adjustment. and auxiliary shortening of the tappet at that pointwill depend of course upon the radial width of the washer and washersmay be selected in accordance with the requirements. Conveniently arelatively narrow washer may be employed for the inlet valves whichcommonly are designed to have a clearance of about .006 inch forexample, and a much wider washer for the exhaust valves in the sameengine, such exhaust valves being designed to have for example aclearance of about .014 inch. The flat type of spring washer suchasemployed at 35 in Fig. 6 has the advantage of being easier and moreeconomical of manufacture than the dished type shown in Figs. 1 and 4.

Fig. 6a shows a similar arrangement but employi ig a washer 35a which isslightly dished, that is, the radial section .shown slopes upwardly tothe right. A small change in the lash or collapsible clearance may beaccomplished by reversing the washer. For example a washer which is .125inch wide with an angle of about one half of one degree will have a riseof about .001 inch and reversing the washer will produce a variation ofabout .002 inch in the lash. An angle of one degree will produce avariation of about .004 inch upon reversal of the washer. Majorvariations in the clearance may be obtained by using a plurality ofwashers in different superposed relation. Fig. 7 shows two flat springsteel washers 36 and an intervening dished washer 37. The latter is notdesigned to flex and may be made of ordinary soft iron and substantialthickness and therefore cheaper. For example the thickness of the dishedwasher 37 may be in the order of 4 inch and that of the spring washers36 about .020 inch. Itwill be understood that Fig. 7

.and likewise Figs. 6 and 6a are not in accurate propormeans may beobtained by variation in the radial width of the spring washers.

The valve body 2 and the parts associated therewith are raised andlowered by the rotation of a cam 23 in the usual manner. The stem 24 ofan engine valve is engaged at its lower end by the upper side of thehead '6 of the described screw, the usual heavy spring 26 beingassociated with the valve and which when free to do so will close thevalve 25 against its seat to make a tight closing engagement therewith.

The flanges 17 and 20 cut away as indicated at 18 on the flange 17, andsimilarly on the flange 20, facilitate the assembly of the spring 19with the sleeve 4 and nut 14, as the ends of the end coils of thesprings may be readily introduced to pass under flange 17 and overflange 20 and be turned until a sufiicient number of the end coils arearound such nut and the upper portion of.

the sleeve-4am connect therewith with a tight binding engagement. Asheretofore described the tension of spring 19 is adjusted to the desireddegree by ratcheting the hook end 19a backward over the shouldersprovided by the recesses 16 in the nut 14. The spring is assembled undera pre-load of suflicient amount to cause an 'u'pw'ardpush of the screwwith a force of from 3 to 12 pounds in practice.

In the operation, with the tappet in its lowermost position as in Fig.1, and with the circular or base circle portion of cam 23 bearingagainst the side in of the body, the weight .12 is at its lower positionhanging upon and being supported by the pin 11. On rotation of the camto lift the tappet such weight remains in lower position until theuppermost position of the tappet is reached.

.At the peak of its rise against the cam the tappet body stops and theweight 12, due to the momentum of its upward movement, moves upwardly onthe section of the screw and strikes against the lower side of the nut14, at which time the weight is moving solely in a vertical direction,as the pin 11 (Fig. 2) is in the substantially vertical lower endportion of the slot 13. The weight remains in such position as thetappet body and other parts associated therewith move downwardly withaccelerated speed, until the tappet has reached its lowermost positionand is stopped against further downward movement, resting upon thecircular or base circle portion of the cam. The weight thereupon movesdownwardly and is spun about the vertical axis of the screw, strikingthe pin 11 at the upper closed end of the slot 1 3'with an impactforcein a horizontal direction, which turns the screw. Assuming that thetappet is the right length oris slightly too long, the flange 5 of thenut will be compressed into frictional engagement with the supportingshoulder. of the tappet body, or the spring washer 22 or equivalent formof washer if one is employed, and the screw 7 will turn in the sleeve ornut 4 in a downward direction to shorten the effective length of thetappet making a clearance between the valve stem 24 and the head 6 ofthe screw. This insures that the valve will reach and properly engageits seat so as to close the port of the engine at which the valve islocated.

immediately following, while the lower end of the body 1 is upon thecircular or base circle portion of the cam 23, such clearance isautomatically taken up by the torsion spring 19 which will causerelative turning between the nut 4 and the screw 7 in the lengtheningdirection until the head 6 comes against the lower end of valve stem 24.Any difference between the amount that the screw is thus wound back bythe spring 19, and that it was operated in the opposite direction by theimpact of the weight 12 on the pin is the amount of valve growth on thepreceding cycle of the engine.

A further operational characteristic of the tappet will now bedescribed. As previously pointed out the annular flange 5 of the nut 4has an outer diameter slightly less than the interior diameter of theupper portion of the body 2 in which it is located and accordingly isrelatively free to rotate therein when not forced into frictionalengagement with its seat. The importance of this may be demonstrated bya review of certain features of the operation. There is a time elementinvolved in which the torsion spring 19 normally must stop the rotationof the screw caused by the inertia member 12 and effect a reverserotation to restore the screw relative to the nut to at least theapproximate original position. Although the time element is only afraction of a second, it nevertheless is substantial and material and,particularly at high speed of the engine, there might not be sufricienttime to effect the necessary amount ofreverse rotation to accomplish therequired lengthening. This may result, therefore, in the tappetcontinuing to produce even aunet shortening of the tappet although itwas already short enough. By having, however, thenut free toturn in thebody of the tappet when there is no vertical force thereon, then whenthe weight 12 strikes the pin 11 and causes the screw to turn, thetorque will likewise be transmitted to the nut through the spring andalso the effect of the friction at the screw threads, causing the nut toturn with the screw. Therefore there would be little or no shortening ofthe tappet but there would be an appreciable time for some lengtheningat each cycle. In other words, if the tappet were already short enough,and particularly it it were too short, there would be no overshorteningand the length would be progressively increased in rapid order to aproper operating condition.

The above, of course, only occurs when there is practically no pressureon the screw from the valve stem since if there is continued pressureafter the valve seats then the frictional engagement of the flange 5 onits support holds the nut against rotation and the screw will turn inthe nut upon impact of the weight. In this respect it is noted that anyfrictional resistance at the flange 22 is effective at a longer torquearm than the frictional resistance at the threads tending to turn thenut. Therefore, when there is weight applied to the screw it will turnin the nut, because the relatively light tension of the torsion spring19 is not sufficient to overcome the friction of the nut at its supportin the body. In general the tappet functions automatically in accordancewith the requirements. If the tappet is too short then the nut turns andover-shortening is avoided and the tappet is quickly lengthened to theproper condition, but if the tappet is too long the nut is restrainedand a certain amount of shortening each cycle is assured to achieve theproper operating condition.

An important feature in connection with the combination and operationjust described is the selection of a thread of proper pitch. The screwas commonly employed has a diameter of about of an inch, and it has beenfound that the pitch should be in the range of 10 to 32 3 threads to theinch. The slope on such a thread is a little less than 5 for a pitch of10 threads and about 1 /2 for a pitch of 32 threads. It is quitepreferable, however, to keep the pitch within the narrower range of 16to 24 threads to the inch which corresponds to about 3 to 2. With afiner thread than 24 to the inch the reduction in length resulting froma given relative angular adjustment between the screw and nut effectedby the impact of the weight is small and the shortening may be too slow.On the other hand, normally with a coarse pitch screw having a greaterinclination the screw turns more easily in the nut under axial thrustand the inertia weight may cause the screw to turn too far into the nutsuch that at high engine speeds there is not sufficient time forcomplete restoration. With the construction described, however, having anut freely mounted a relative steep pitch, such as 16 threads to theinch with a slope of about 3", may be employed.

A feature which cooperates with the above described elements andcharacteristics to insure unvarying dependable operation is theprovision of the inclined bottom on the tappet body or shell whichhouses the screw sub-assembly, to maintain the tappet against notationwhich would normally occur from the actionof the cam. The rotation ofthe screw '7 under the effect of the weight and the torsionspring, andthe rotation of the nut are matters of relative rotation and action, andany rotation of the tappet body would necessarily have its effect. Ifthe action of the cam were such as to rotate the tappet at a constantuniform speed and in a single direction then it would be possible tocompensate therefor in the proportions and characteristics of the innerworking parts such that the inertia hammer and associated parts wouldfunction satisfactorily. But with a normal square bottom tappet body orshell, e.g. the friction and pressure forces acting thereon tending tocause rotation are variable and .irnpact end-in the range of 40 to 50".

"7 further are subject to change under conditions of wear and use overperiods of time, and correspondingly the rotation of the tappet may bevariable and erratic, with corresponding effect on the functioning ofthe length compensating means. Furthermore there is a substantial amountof friction between the upper surface of the tappet adjusting screw andthe contacting element in the valve operating linkage and if the tappetwere caused to rotate this would tend to cause the screw to be threadedinto, or out of, its nut as the case might be and which wouldcorrespondingly oppose or amplify the effect of the inertia compensatingmeans. The inclined bottom contact face of the tappet shell, designed tomaintain the cam engaging lifter element against rotation, cooperates ina very desirable manner in rendering the operation uniform anddependable. This feature is of importance whether the compensatingelement is located to contact the cam, or at some other point in theoperating linkage as will be described in connection with Fig. 5. Insome installations the rotational forces may be so strong or otherconditions exist such that it is impractical to attempt to preventrotation by means of the inclined contact face. Increasing the amount ofthe angle increases the ability of the tappet to resist spinning but anangle larger than a particular value may result in disturbance of theoriginally designed valve timing. The limit in this respect will vary indifferent cases but an' angle greater than about is seldom practical andusually the angle should be in the range below about 2.

It is of course apparent that when the clearance between the valve stem24 and the head 6 of the screw occurs through the impact of the weight12 against the pin 11, 'the washer or washers 22 of Fig. 1, orcorresponding washers of other figures, in those installations wherethey are used, will tend to resume their normal position, and the returnof the screw'head 6 against the head of the valve stem 24 will be withthe ring 3 and flange 5 separated as shown in Fig. 1, thereby providingthe constant clearance required for running on the cams of a cam shaftdesigned to accommodate standard lash type lifters. Such washer orwashers are completely collapsed when, upon the upward movement or liftof the tappet, the force of the valve spring 26 comes into actionholding the valve closed until such collapse has occurred after whichthe valve is lifted. V

The weight 12 and the slot 13 therein embody features which contributeto the best operation of the device. The slot 13 has aconstant radiusand such slot is located in such a manner as to allow the upper closedend of the slot to strike the pin a blow having a component in thehorizontal direction to wind the torsion spring 19. The lower end of theslot is located so that in association with .the pin 11 the weight isimpelled to move vertically until the upper surface of the weight 12abuts the lower surface of the nut 14. Some variation is permissible inthe angle of the different portions of the slot butin general the anglewith respect to a radial plane through the axis of the screw shouldpreferably be, at the bottom open end portion, in the range of O" to 20,and at the upper The slot 13 should be located and shaped to providesubstantially a line contact with the pin along its extent to insure afreely sliding engagement, and particularly at the closed end of theslot to eliminate a cushion action at the critical moment of impact whenthe parts are covered with lubricating oil. Such a shape is shown in thecross secbe conveniently formed by a tapered milling cutter whichprovides line contacts for the pin 11, as indicated at 13a,

as it advances along the slot, and at the end of the slot as indicatedat 13b (Fig. 2).

-The compensating device has been described and is adapted, however, tobe inserted at other points in the i tional view of Fig. 8. Since theslot is open ended it may linkage and FigIS illustrates one such otherinstallation. The general arrangement embodies an overhead valve 40, andan operating linkage which includes ,a rocker arm 41, and vertical rodmembers having a mushroom type tappet 42with a. base adapted to engagecam 43. Typical of various original designs and installations thetappet.42 has a small stem making it difiicult to install a replacementcompensating tappet at that point. Such a compensating means, however,is shown inserted in the linkage at 44 with a connecting rod45 ofappropriate length extending between it and the tappet 42. Thecompensating device 44 is constructed interiorly similarly to that shownin Figs. 1 to 3 but is modified otherwise to connect appropriately withthe rocker arm 41 and rod 45. The upper end 46 of the adjusting screwhas e.g. a socket in which fits the rounded lower end of a set screwsecured in the rocker arm, and the bottom of the body of the compensatorhas a similar socket to receive the upper rounded end of rod 45. Thelower end of rod 45 is similarly fitted in the upper end of tappet.Suitable passages may be provided to conduct lubricating oil from therocker arm through the successiveelements to the tappet 42.

In the normal original engine designs such as that shown, the tappetusually has a bottom which is fiat and therefore permits rotation, or itmay have a special shape to accentuate the rotation for known reasons.By reason of the unavoidable frictional effects between the contactingends of the linkage elements including the engagement of the upper endof rod 45 with the bottom of the compensating element 44 such rotationwould be transmitted in variable degree to the element 44. This isprevented in the apparatus of Fig. 5 by substituting for the original atappet 42 having a bottom inclined similarly to the inclination on thebottom surface of the body or shell 2 in Fig. 1. In other words, theplane of the bottom indicated by the line 48 is inclined to a plane 49perpendicular to the axis of the tappet by angle A which is of the orderindicated in connection with the body or shell 2 of Fig. 1. The positionof the tappet 42 and the showing of the angle of inclination A assumesthat the cam 43 normally rotates in a clockwise direction.

With the length compensating means described, changes in longitudinaldimensions of the valve stem and all elements in the valve operatinglinkage are fully compensated for and the elements are maintained incontact and perfect valve timing is correspondingly maintained withconsequent maximum engine efliciency. The only clearance which takesplace between the screw head and the valve stem or push rod is forsubstantially an instant of time as the tappet reaches its lowermostposition to insure positive and complete setting of the valve againstits seat, with substantially instantaneous closing of such clearancethrough the action of the spring 19. Such clearance and its closureoccurs at each cycle of engine operation and insures that under alltemperature and other conditions of the engine the tappet, when liftingthe valve and for a short period of time before the lifting occurs, willbe in contact with the valve stem or push rod and there will be nonoises of impingement of the head of the screw against valve stem orpush rod during the time that the longitudinal expansion of valve stemor push rod occurs after starting a cold engine and until it is fullywarmed up; or at other times when tappets are faultily adjusted. Of evenmore importance is the fact that the present tappetassures that theengine valves will be seated at the proper time and, in addition totheresulting increased engine efiiciency, it avoids the major noise causedby a valve striking its seat at high velocity when it reaches itsv seattoo early while the tappet is riding on a steeper Pfiflofthe cam. Thetappet is noiseless, is far simpler in structure and operation than ahydraulic tappet, less liable to get out of order and 9 need repair orreplacement, more economical to produce and serves fully every purpose,function and effect, insofar as elimination of noise and assuring propervalve operation are concerned, as do hydraulic tappets. Also hydraulictappets are prone to leak down oil therein when stopped at any portionof the associated cam rise, which is eliminated with the present tappet,which does not have oil leakage.

The invention is defined in the appended claims and is to be consideredcomprehensive of all forms of structure coming within their scope.

I claim: a

1. In a length compensating device adapted to be embodied in an axiallyreciprocatory valve linkage, cooperating male and female screw membershaving a threaded connection with a thread pitch in the range of 10 to32 threads per inch, said members being adapted to be threaded togetherin one direction to shorten the linkage and being provided with atorsion spring connecting said members normally tending to effect arelative rotation in the opposite direction to lengthen the linkage, afirst one of said members being adapted to have thrust applied directlyto the end thereof, an axial support for the other member said othermember being freely rotatable in said support when relieved of axialthrust.

2. In a length compensating device adapted to be embodied in an axiallyreciprocatory valve linkage, cooperating male and female screw membershaving a threaded connection with a slope in the range of 1 /2 to 5degrees, said members being adapted to be threaded together in onerelative direction to shorten the linkage and being provided with atorsion spring connecting said members normally tending to effect arelative rotation in the opposite direction to lengthen the linkage,said male member being adapted to receive axial thrust in the linkage,and a support for said female member with a seat for engaging a portionof the female member and supporting the latter against axial thrust,said female member being rotatable on the seat when free of axialthrust.

3. In a linkage length compensating device adapted to be embodied in anaxially reciprocatory valve linkage, the combination of a sub-assemblycomprising cooperating male and female screw members having a threadedconnection with a slope in the range of 2 to 3, a torsion springconnecting said members, a first one of said members being adapted tohave thrust applied to the end thereof, an inertia hammer means adaptedto act upon said first member and effect rotation thereof against thespring torsion in the direction of threading the members together, andan axial support for the second one of said members with the latterbeing freely rotatable therein when unloaded whereby said sub-assemblywill rotate in said support under the influence of said inertia hammermeans during periods of freedom from axial thrust in the linkage.

4. In a linkage length compensating device, an open ended hollowsupporting body, cooperating male and female screw members thereinhaving a threaded connection with a slope of about 3, said female memberhaving an enlarged flange portion adapted to be sup ported on a shoulderin said body, a torsion spring connecting said members, said male memberhaving means adapted to receive axial thrust in the linkage and transmitit to said flange portion to force it down upon said shoulder, saidfemale member being freely rotatable with respect to said supportingshoulder when relieved of axial thust but restrained against rotation byfrictional engagement at said flange when subjected to axial thrust, andan inertia hammer means adapted to act on said male member to rotate itagainst the spring torsion in the direction of threading said memberstogether when said female member is restrained against rotation, saidfemale directly 10 member being permitted to rotate with said malemember when free of axial thrust.

5. In a linkage length compensating device embodying an inertialengthadjusting means, cooperating male and female screw members, a'torsionspringconnectedto said members to effect relative rotation in thelengthening direction, an inertia hammer mounted on one of said membersslidable coaxially thereof, a pin extending radially from the lattersaid member, said hammer having a radial slot to receive the pin,'saidslot extending axially thereof and having a portion spiralled withrespect to the axis and terminating in a closed end adapted to strikethe pin and cause rotation of the pin and thereby of the said lattermember in a direction opposite to said spring, said slot along the sidesand at the closed end being shaped to present substantially a linecontact with said pin.

6. In a linkage length compensating device embodying an inertia lengthadjusting means,cooperating male and female screw members, a torsionspring connected to said members to effect relative rotation in thelengthening direction, an inertia hammer in the form of a sleeve mountedon one of said members slidable coaxially there of, a pin extendingradially from the latter member, said hammer having a radial slot toreceive the pin, said slot being open ended at one edge of said sleeveand extending axially of the sleeve with a spiralled closed end, thespiralled end being arranged to effect a rotation of the sleeve as itadvances and imparts a rotative impact on the pin as it is engaged bythe end of the slot and thereby to cause rotation of the said lattermember in a direction opposite to said spring, said slot along the sidesand at the closed end being shaped to present substantially a linecontact with said pin.

7. In a linkage length compensating device embodying an inertia lengthadjusting means, cooperating male and female screw members, a torsionspring connected to said members to effect relative rotation in thelengthening direction, an inertia hammer comprising a sleeve mountedcoaxially of one of said members slidable vertically thereof, a pinextending radially from the latter member, said sleeve having a radialslot to receive the pin, said slot being open ended at the bottom andextending along a spiral path upwardly axially of the sleeve to a closedupper impact end, the bottom portion of said slot being arranged at anangle in the range of 0 to 20 with respect to a plane through the axisof the sleeve and the upper portion thereof adjacent the closed endbeing ar ranged at an angle in the range of 40 to 50 with respect tosuch a plane, said slot along the sides and at the closed end beingshaped to present substantially a line contact with said pin.

8. In a length compensating device the combination of, a pair ofconcentric members having complemental opposed conical surfaces and acollapsible intervening spring means comprising a pair of substantiallyflat flexible washers, and a spacer washer between the two flexiblewashers having a conical shape substantially corresponding to theinclined shape of the said opposed surfaces of said members.

9. In a length compensating device the combination of, a hollowcylindrical body member, an inner member axially movable within andconcentrically of said body member, said members having opposed annularsurfaces similarly inclined to form complemental conical seats; a

and an intervening spring means comprising a pair of substantially flatflexible washers, and a relatively inflexible spacer washer between thetwo flexible washers hav-' ing a conical shape substantially similar tothat of said opposed surfaces.

10. In a length compensating device the combination comprising; a hollowcylindrical shell; an annular shoulder in said shell having an outwardconcave, substantially conical surface; an inner member telescopicallyreceived in said shell with clearance; an annular filange on said 7References Cited in the file of this patent UNITED STATES PATENTS WareFeb. 13,1923 Tucker Mar. 31, 1931 Holmes 'Jan. 5, 1937 Holmes et al'Apr. 29, 1941 Engemann Mar. 10, 1953 Engemann Mar. 31, 1953 Pearson May24, 1955

